IMO Ubuntu is great for beginners. I started off with Ubuntu about 5 years ago, and never looked back. I've tried other distros, but always had this thing for Ubuntu, I use it on my desktop and I have the Server Edition for my RackMount Servers.
It's very user friendly and easy to manage.
Distribution is upgraded every 6 months and Ubuntu 10.04 for example, in 6 months can be upgraded to 10.10 just by using the Update Manager tool, no need to get the new CD.
If you want to get more into Linux and start running servers, I have 3 servers, 1 IRCd+IRC Services+IRC Stats+IRC Bouncer, one as a home server + Proxy + SSH gateway to my other servers and desktop system, and one server for my websites, more MySQL DB's, and general testing.
If you ever need any help join me at irc.i-have-no.info in #Linux